In recent years, so-called “hybrid vehicles” have become increasingly popular. These vehicles typically supplement the power produced by a more-conventional internal combustion engine with power generated by one or more electric motors, thereby dramatically reducing fuel consumption without significant effects upon the driving experience.
Despite the success of hybrid and electric vehicles, however, various design and performance challenges remain. For example, thermal issues often arise within power module circuits associated with electric motors because the various components (e.g. transistors, diodes) present within the inverter circuit tend to dissipate heat energy at uneven rates, particularly at low fundamental operating frequencies. Typically, it is desirable to avoid overheating the various components in the power module to prevent damage. While many power module controllers implement some sort of thermal protection, this is typically based upon an internally-mounted thermistor and/or average heat dissipation over a period of the fundamental output of the module. Such techniques generally assume that the frequency of the output is high relative to a thermal time-constant of the component so that the device temperature is averaged over time. At very low frequency operation (e.g., very low speed or standstill conditions), however, this averaging assumption may not hold, thereby leading to inaccurate temperature estimations. Inaccurate estimation could potentially lead to undesirable overloading of one or more components of the system, which could, over time, result in reduced reliability of such components.
Accordingly, it is desirable to provide improved systems and techniques for estimating thermal conditions of components within the power module system. In particular, it is desirable to create systems and techniques that provide accurate temperature estimation even at relatively low fundamental operating frequencies (such as zero hertz). Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.